2 * linux/kernel/seccomp.c
4 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
6 * Copyright (C) 2012 Google, Inc.
7 * Will Drewry <wad@chromium.org>
9 * This defines a simple but solid secure-computing facility.
11 * Mode 1 uses a fixed list of allowed system calls.
12 * Mode 2 allows user-defined system call filters in the form
13 * of Berkeley Packet Filters/Linux Socket Filters.
16 #include <linux/refcount.h>
17 #include <linux/audit.h>
18 #include <linux/compat.h>
19 #include <linux/coredump.h>
20 #include <linux/kmemleak.h>
21 #include <linux/sched.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/seccomp.h>
24 #include <linux/slab.h>
25 #include <linux/syscalls.h>
26 #include <linux/sysctl.h>
28 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
29 #include <asm/syscall.h>
32 #ifdef CONFIG_SECCOMP_FILTER
33 #include <linux/filter.h>
34 #include <linux/pid.h>
35 #include <linux/ptrace.h>
36 #include <linux/security.h>
37 #include <linux/tracehook.h>
38 #include <linux/uaccess.h>
41 * struct seccomp_filter - container for seccomp BPF programs
43 * @usage: reference count to manage the object lifetime.
44 * get/put helpers should be used when accessing an instance
45 * outside of a lifetime-guarded section. In general, this
46 * is only needed for handling filters shared across tasks.
47 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
48 * @prev: points to a previously installed, or inherited, filter
49 * @prog: the BPF program to evaluate
51 * seccomp_filter objects are organized in a tree linked via the @prev
52 * pointer. For any task, it appears to be a singly-linked list starting
53 * with current->seccomp.filter, the most recently attached or inherited filter.
54 * However, multiple filters may share a @prev node, by way of fork(), which
55 * results in a unidirectional tree existing in memory. This is similar to
56 * how namespaces work.
58 * seccomp_filter objects should never be modified after being attached
59 * to a task_struct (other than @usage).
61 struct seccomp_filter
{
64 struct seccomp_filter
*prev
;
65 struct bpf_prog
*prog
;
68 /* Limit any path through the tree to 256KB worth of instructions. */
69 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
72 * Endianness is explicitly ignored and left for BPF program authors to manage
73 * as per the specific architecture.
75 static void populate_seccomp_data(struct seccomp_data
*sd
)
77 struct task_struct
*task
= current
;
78 struct pt_regs
*regs
= task_pt_regs(task
);
79 unsigned long args
[6];
81 sd
->nr
= syscall_get_nr(task
, regs
);
82 sd
->arch
= syscall_get_arch();
83 syscall_get_arguments(task
, regs
, 0, 6, args
);
84 sd
->args
[0] = args
[0];
85 sd
->args
[1] = args
[1];
86 sd
->args
[2] = args
[2];
87 sd
->args
[3] = args
[3];
88 sd
->args
[4] = args
[4];
89 sd
->args
[5] = args
[5];
90 sd
->instruction_pointer
= KSTK_EIP(task
);
94 * seccomp_check_filter - verify seccomp filter code
95 * @filter: filter to verify
96 * @flen: length of filter
98 * Takes a previously checked filter (by bpf_check_classic) and
99 * redirects all filter code that loads struct sk_buff data
100 * and related data through seccomp_bpf_load. It also
101 * enforces length and alignment checking of those loads.
103 * Returns 0 if the rule set is legal or -EINVAL if not.
105 static int seccomp_check_filter(struct sock_filter
*filter
, unsigned int flen
)
108 for (pc
= 0; pc
< flen
; pc
++) {
109 struct sock_filter
*ftest
= &filter
[pc
];
110 u16 code
= ftest
->code
;
114 case BPF_LD
| BPF_W
| BPF_ABS
:
115 ftest
->code
= BPF_LDX
| BPF_W
| BPF_ABS
;
116 /* 32-bit aligned and not out of bounds. */
117 if (k
>= sizeof(struct seccomp_data
) || k
& 3)
120 case BPF_LD
| BPF_W
| BPF_LEN
:
121 ftest
->code
= BPF_LD
| BPF_IMM
;
122 ftest
->k
= sizeof(struct seccomp_data
);
124 case BPF_LDX
| BPF_W
| BPF_LEN
:
125 ftest
->code
= BPF_LDX
| BPF_IMM
;
126 ftest
->k
= sizeof(struct seccomp_data
);
128 /* Explicitly include allowed calls. */
129 case BPF_RET
| BPF_K
:
130 case BPF_RET
| BPF_A
:
131 case BPF_ALU
| BPF_ADD
| BPF_K
:
132 case BPF_ALU
| BPF_ADD
| BPF_X
:
133 case BPF_ALU
| BPF_SUB
| BPF_K
:
134 case BPF_ALU
| BPF_SUB
| BPF_X
:
135 case BPF_ALU
| BPF_MUL
| BPF_K
:
136 case BPF_ALU
| BPF_MUL
| BPF_X
:
137 case BPF_ALU
| BPF_DIV
| BPF_K
:
138 case BPF_ALU
| BPF_DIV
| BPF_X
:
139 case BPF_ALU
| BPF_AND
| BPF_K
:
140 case BPF_ALU
| BPF_AND
| BPF_X
:
141 case BPF_ALU
| BPF_OR
| BPF_K
:
142 case BPF_ALU
| BPF_OR
| BPF_X
:
143 case BPF_ALU
| BPF_XOR
| BPF_K
:
144 case BPF_ALU
| BPF_XOR
| BPF_X
:
145 case BPF_ALU
| BPF_LSH
| BPF_K
:
146 case BPF_ALU
| BPF_LSH
| BPF_X
:
147 case BPF_ALU
| BPF_RSH
| BPF_K
:
148 case BPF_ALU
| BPF_RSH
| BPF_X
:
149 case BPF_ALU
| BPF_NEG
:
150 case BPF_LD
| BPF_IMM
:
151 case BPF_LDX
| BPF_IMM
:
152 case BPF_MISC
| BPF_TAX
:
153 case BPF_MISC
| BPF_TXA
:
154 case BPF_LD
| BPF_MEM
:
155 case BPF_LDX
| BPF_MEM
:
158 case BPF_JMP
| BPF_JA
:
159 case BPF_JMP
| BPF_JEQ
| BPF_K
:
160 case BPF_JMP
| BPF_JEQ
| BPF_X
:
161 case BPF_JMP
| BPF_JGE
| BPF_K
:
162 case BPF_JMP
| BPF_JGE
| BPF_X
:
163 case BPF_JMP
| BPF_JGT
| BPF_K
:
164 case BPF_JMP
| BPF_JGT
| BPF_X
:
165 case BPF_JMP
| BPF_JSET
| BPF_K
:
166 case BPF_JMP
| BPF_JSET
| BPF_X
:
176 * seccomp_run_filters - evaluates all seccomp filters against @sd
177 * @sd: optional seccomp data to be passed to filters
178 * @match: stores struct seccomp_filter that resulted in the return value,
179 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
182 * Returns valid seccomp BPF response codes.
184 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
185 static u32
seccomp_run_filters(const struct seccomp_data
*sd
,
186 struct seccomp_filter
**match
)
188 struct seccomp_data sd_local
;
189 u32 ret
= SECCOMP_RET_ALLOW
;
190 /* Make sure cross-thread synced filter points somewhere sane. */
191 struct seccomp_filter
*f
=
192 lockless_dereference(current
->seccomp
.filter
);
194 /* Ensure unexpected behavior doesn't result in failing open. */
195 if (unlikely(WARN_ON(f
== NULL
)))
196 return SECCOMP_RET_KILL_PROCESS
;
199 populate_seccomp_data(&sd_local
);
204 * All filters in the list are evaluated and the lowest BPF return
205 * value always takes priority (ignoring the DATA).
207 for (; f
; f
= f
->prev
) {
208 u32 cur_ret
= BPF_PROG_RUN(f
->prog
, sd
);
210 if (ACTION_ONLY(cur_ret
) < ACTION_ONLY(ret
)) {
217 #endif /* CONFIG_SECCOMP_FILTER */
219 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode
)
221 assert_spin_locked(¤t
->sighand
->siglock
);
223 if (current
->seccomp
.mode
&& current
->seccomp
.mode
!= seccomp_mode
)
229 static inline void seccomp_assign_mode(struct task_struct
*task
,
230 unsigned long seccomp_mode
)
232 assert_spin_locked(&task
->sighand
->siglock
);
234 task
->seccomp
.mode
= seccomp_mode
;
236 * Make sure TIF_SECCOMP cannot be set before the mode (and
239 smp_mb__before_atomic();
240 set_tsk_thread_flag(task
, TIF_SECCOMP
);
243 #ifdef CONFIG_SECCOMP_FILTER
244 /* Returns 1 if the parent is an ancestor of the child. */
245 static int is_ancestor(struct seccomp_filter
*parent
,
246 struct seccomp_filter
*child
)
248 /* NULL is the root ancestor. */
251 for (; child
; child
= child
->prev
)
258 * seccomp_can_sync_threads: checks if all threads can be synchronized
260 * Expects sighand and cred_guard_mutex locks to be held.
262 * Returns 0 on success, -ve on error, or the pid of a thread which was
263 * either not in the correct seccomp mode or it did not have an ancestral
266 static inline pid_t
seccomp_can_sync_threads(void)
268 struct task_struct
*thread
, *caller
;
270 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
271 assert_spin_locked(¤t
->sighand
->siglock
);
273 /* Validate all threads being eligible for synchronization. */
275 for_each_thread(caller
, thread
) {
278 /* Skip current, since it is initiating the sync. */
279 if (thread
== caller
)
282 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
||
283 (thread
->seccomp
.mode
== SECCOMP_MODE_FILTER
&&
284 is_ancestor(thread
->seccomp
.filter
,
285 caller
->seccomp
.filter
)))
288 /* Return the first thread that cannot be synchronized. */
289 failed
= task_pid_vnr(thread
);
290 /* If the pid cannot be resolved, then return -ESRCH */
291 if (unlikely(WARN_ON(failed
== 0)))
300 * seccomp_sync_threads: sets all threads to use current's filter
302 * Expects sighand and cred_guard_mutex locks to be held, and for
303 * seccomp_can_sync_threads() to have returned success already
304 * without dropping the locks.
307 static inline void seccomp_sync_threads(void)
309 struct task_struct
*thread
, *caller
;
311 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
312 assert_spin_locked(¤t
->sighand
->siglock
);
314 /* Synchronize all threads. */
316 for_each_thread(caller
, thread
) {
317 /* Skip current, since it needs no changes. */
318 if (thread
== caller
)
321 /* Get a task reference for the new leaf node. */
322 get_seccomp_filter(caller
);
324 * Drop the task reference to the shared ancestor since
325 * current's path will hold a reference. (This also
326 * allows a put before the assignment.)
328 put_seccomp_filter(thread
);
329 smp_store_release(&thread
->seccomp
.filter
,
330 caller
->seccomp
.filter
);
333 * Don't let an unprivileged task work around
334 * the no_new_privs restriction by creating
335 * a thread that sets it up, enters seccomp,
338 if (task_no_new_privs(caller
))
339 task_set_no_new_privs(thread
);
342 * Opt the other thread into seccomp if needed.
343 * As threads are considered to be trust-realm
344 * equivalent (see ptrace_may_access), it is safe to
345 * allow one thread to transition the other.
347 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
)
348 seccomp_assign_mode(thread
, SECCOMP_MODE_FILTER
);
353 * seccomp_prepare_filter: Prepares a seccomp filter for use.
354 * @fprog: BPF program to install
356 * Returns filter on success or an ERR_PTR on failure.
358 static struct seccomp_filter
*seccomp_prepare_filter(struct sock_fprog
*fprog
)
360 struct seccomp_filter
*sfilter
;
362 const bool save_orig
= IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
);
364 if (fprog
->len
== 0 || fprog
->len
> BPF_MAXINSNS
)
365 return ERR_PTR(-EINVAL
);
367 BUG_ON(INT_MAX
/ fprog
->len
< sizeof(struct sock_filter
));
370 * Installing a seccomp filter requires that the task has
371 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
372 * This avoids scenarios where unprivileged tasks can affect the
373 * behavior of privileged children.
375 if (!task_no_new_privs(current
) &&
376 security_capable_noaudit(current_cred(), current_user_ns(),
378 return ERR_PTR(-EACCES
);
380 /* Allocate a new seccomp_filter */
381 sfilter
= kzalloc(sizeof(*sfilter
), GFP_KERNEL
| __GFP_NOWARN
);
383 return ERR_PTR(-ENOMEM
);
385 ret
= bpf_prog_create_from_user(&sfilter
->prog
, fprog
,
386 seccomp_check_filter
, save_orig
);
392 refcount_set(&sfilter
->usage
, 1);
398 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
399 * @user_filter: pointer to the user data containing a sock_fprog.
401 * Returns 0 on success and non-zero otherwise.
403 static struct seccomp_filter
*
404 seccomp_prepare_user_filter(const char __user
*user_filter
)
406 struct sock_fprog fprog
;
407 struct seccomp_filter
*filter
= ERR_PTR(-EFAULT
);
410 if (in_compat_syscall()) {
411 struct compat_sock_fprog fprog32
;
412 if (copy_from_user(&fprog32
, user_filter
, sizeof(fprog32
)))
414 fprog
.len
= fprog32
.len
;
415 fprog
.filter
= compat_ptr(fprog32
.filter
);
416 } else /* falls through to the if below. */
418 if (copy_from_user(&fprog
, user_filter
, sizeof(fprog
)))
420 filter
= seccomp_prepare_filter(&fprog
);
426 * seccomp_attach_filter: validate and attach filter
427 * @flags: flags to change filter behavior
428 * @filter: seccomp filter to add to the current process
430 * Caller must be holding current->sighand->siglock lock.
432 * Returns 0 on success, -ve on error.
434 static long seccomp_attach_filter(unsigned int flags
,
435 struct seccomp_filter
*filter
)
437 unsigned long total_insns
;
438 struct seccomp_filter
*walker
;
440 assert_spin_locked(¤t
->sighand
->siglock
);
442 /* Validate resulting filter length. */
443 total_insns
= filter
->prog
->len
;
444 for (walker
= current
->seccomp
.filter
; walker
; walker
= walker
->prev
)
445 total_insns
+= walker
->prog
->len
+ 4; /* 4 instr penalty */
446 if (total_insns
> MAX_INSNS_PER_PATH
)
449 /* If thread sync has been requested, check that it is possible. */
450 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
) {
453 ret
= seccomp_can_sync_threads();
458 /* Set log flag, if present. */
459 if (flags
& SECCOMP_FILTER_FLAG_LOG
)
463 * If there is an existing filter, make it the prev and don't drop its
466 filter
->prev
= current
->seccomp
.filter
;
467 current
->seccomp
.filter
= filter
;
469 /* Now that the new filter is in place, synchronize to all threads. */
470 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
471 seccomp_sync_threads();
476 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
477 void get_seccomp_filter(struct task_struct
*tsk
)
479 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
482 /* Reference count is bounded by the number of total processes. */
483 refcount_inc(&orig
->usage
);
486 static inline void seccomp_filter_free(struct seccomp_filter
*filter
)
489 bpf_prog_destroy(filter
->prog
);
494 /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
495 void put_seccomp_filter(struct task_struct
*tsk
)
497 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
498 /* Clean up single-reference branches iteratively. */
499 while (orig
&& refcount_dec_and_test(&orig
->usage
)) {
500 struct seccomp_filter
*freeme
= orig
;
502 seccomp_filter_free(freeme
);
506 static void seccomp_init_siginfo(siginfo_t
*info
, int syscall
, int reason
)
508 memset(info
, 0, sizeof(*info
));
509 info
->si_signo
= SIGSYS
;
510 info
->si_code
= SYS_SECCOMP
;
511 info
->si_call_addr
= (void __user
*)KSTK_EIP(current
);
512 info
->si_errno
= reason
;
513 info
->si_arch
= syscall_get_arch();
514 info
->si_syscall
= syscall
;
518 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
519 * @syscall: syscall number to send to userland
520 * @reason: filter-supplied reason code to send to userland (via si_errno)
522 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
524 static void seccomp_send_sigsys(int syscall
, int reason
)
527 seccomp_init_siginfo(&info
, syscall
, reason
);
528 force_sig_info(SIGSYS
, &info
, current
);
530 #endif /* CONFIG_SECCOMP_FILTER */
532 /* For use with seccomp_actions_logged */
533 #define SECCOMP_LOG_KILL_PROCESS (1 << 0)
534 #define SECCOMP_LOG_KILL_THREAD (1 << 1)
535 #define SECCOMP_LOG_TRAP (1 << 2)
536 #define SECCOMP_LOG_ERRNO (1 << 3)
537 #define SECCOMP_LOG_TRACE (1 << 4)
538 #define SECCOMP_LOG_LOG (1 << 5)
539 #define SECCOMP_LOG_ALLOW (1 << 6)
541 static u32 seccomp_actions_logged
= SECCOMP_LOG_KILL_PROCESS
|
542 SECCOMP_LOG_KILL_THREAD
|
548 static inline void seccomp_log(unsigned long syscall
, long signr
, u32 action
,
554 case SECCOMP_RET_ALLOW
:
556 case SECCOMP_RET_TRAP
:
557 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRAP
;
559 case SECCOMP_RET_ERRNO
:
560 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_ERRNO
;
562 case SECCOMP_RET_TRACE
:
563 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRACE
;
565 case SECCOMP_RET_LOG
:
566 log
= seccomp_actions_logged
& SECCOMP_LOG_LOG
;
568 case SECCOMP_RET_KILL_THREAD
:
569 log
= seccomp_actions_logged
& SECCOMP_LOG_KILL_THREAD
;
571 case SECCOMP_RET_KILL_PROCESS
:
573 log
= seccomp_actions_logged
& SECCOMP_LOG_KILL_PROCESS
;
577 * Force an audit message to be emitted when the action is RET_KILL_*,
578 * RET_LOG, or the FILTER_FLAG_LOG bit was set and the action is
579 * allowed to be logged by the admin.
582 return __audit_seccomp(syscall
, signr
, action
);
585 * Let the audit subsystem decide if the action should be audited based
586 * on whether the current task itself is being audited.
588 return audit_seccomp(syscall
, signr
, action
);
592 * Secure computing mode 1 allows only read/write/exit/sigreturn.
593 * To be fully secure this must be combined with rlimit
594 * to limit the stack allocations too.
596 static const int mode1_syscalls
[] = {
597 __NR_seccomp_read
, __NR_seccomp_write
, __NR_seccomp_exit
, __NR_seccomp_sigreturn
,
598 0, /* null terminated */
601 static void __secure_computing_strict(int this_syscall
)
603 const int *syscall_whitelist
= mode1_syscalls
;
605 if (in_compat_syscall())
606 syscall_whitelist
= get_compat_mode1_syscalls();
609 if (*syscall_whitelist
== this_syscall
)
611 } while (*++syscall_whitelist
);
616 seccomp_log(this_syscall
, SIGKILL
, SECCOMP_RET_KILL_THREAD
, true);
620 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
621 void secure_computing_strict(int this_syscall
)
623 int mode
= current
->seccomp
.mode
;
625 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
626 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
629 if (mode
== SECCOMP_MODE_DISABLED
)
631 else if (mode
== SECCOMP_MODE_STRICT
)
632 __secure_computing_strict(this_syscall
);
638 #ifdef CONFIG_SECCOMP_FILTER
639 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
640 const bool recheck_after_trace
)
642 u32 filter_ret
, action
;
643 struct seccomp_filter
*match
= NULL
;
647 * Make sure that any changes to mode from another thread have
648 * been seen after TIF_SECCOMP was seen.
652 filter_ret
= seccomp_run_filters(sd
, &match
);
653 data
= filter_ret
& SECCOMP_RET_DATA
;
654 action
= filter_ret
& SECCOMP_RET_ACTION_FULL
;
657 case SECCOMP_RET_ERRNO
:
658 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
659 if (data
> MAX_ERRNO
)
661 syscall_set_return_value(current
, task_pt_regs(current
),
665 case SECCOMP_RET_TRAP
:
666 /* Show the handler the original registers. */
667 syscall_rollback(current
, task_pt_regs(current
));
668 /* Let the filter pass back 16 bits of data. */
669 seccomp_send_sigsys(this_syscall
, data
);
672 case SECCOMP_RET_TRACE
:
673 /* We've been put in this state by the ptracer already. */
674 if (recheck_after_trace
)
677 /* ENOSYS these calls if there is no tracer attached. */
678 if (!ptrace_event_enabled(current
, PTRACE_EVENT_SECCOMP
)) {
679 syscall_set_return_value(current
,
680 task_pt_regs(current
),
685 /* Allow the BPF to provide the event message */
686 ptrace_event(PTRACE_EVENT_SECCOMP
, data
);
688 * The delivery of a fatal signal during event
689 * notification may silently skip tracer notification,
690 * which could leave us with a potentially unmodified
691 * syscall that the tracer would have liked to have
692 * changed. Since the process is about to die, we just
693 * force the syscall to be skipped and let the signal
694 * kill the process and correctly handle any tracer exit
697 if (fatal_signal_pending(current
))
699 /* Check if the tracer forced the syscall to be skipped. */
700 this_syscall
= syscall_get_nr(current
, task_pt_regs(current
));
701 if (this_syscall
< 0)
705 * Recheck the syscall, since it may have changed. This
706 * intentionally uses a NULL struct seccomp_data to force
707 * a reload of all registers. This does not goto skip since
708 * a skip would have already been reported.
710 if (__seccomp_filter(this_syscall
, NULL
, true))
715 case SECCOMP_RET_LOG
:
716 seccomp_log(this_syscall
, 0, action
, true);
719 case SECCOMP_RET_ALLOW
:
721 * Note that the "match" filter will always be NULL for
722 * this action since SECCOMP_RET_ALLOW is the starting
723 * state in seccomp_run_filters().
727 case SECCOMP_RET_KILL_THREAD
:
728 case SECCOMP_RET_KILL_PROCESS
:
730 seccomp_log(this_syscall
, SIGSYS
, action
, true);
731 /* Dump core only if this is the last remaining thread. */
732 if (action
== SECCOMP_RET_KILL_PROCESS
||
733 get_nr_threads(current
) == 1) {
736 /* Show the original registers in the dump. */
737 syscall_rollback(current
, task_pt_regs(current
));
738 /* Trigger a manual coredump since do_exit skips it. */
739 seccomp_init_siginfo(&info
, this_syscall
, data
);
742 if (action
== SECCOMP_RET_KILL_PROCESS
)
743 do_group_exit(SIGSYS
);
751 seccomp_log(this_syscall
, 0, action
, match
? match
->log
: false);
755 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
756 const bool recheck_after_trace
)
762 int __secure_computing(const struct seccomp_data
*sd
)
764 int mode
= current
->seccomp
.mode
;
767 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
768 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
771 this_syscall
= sd
? sd
->nr
:
772 syscall_get_nr(current
, task_pt_regs(current
));
775 case SECCOMP_MODE_STRICT
:
776 __secure_computing_strict(this_syscall
); /* may call do_exit */
778 case SECCOMP_MODE_FILTER
:
779 return __seccomp_filter(this_syscall
, sd
, false);
784 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
786 long prctl_get_seccomp(void)
788 return current
->seccomp
.mode
;
792 * seccomp_set_mode_strict: internal function for setting strict seccomp
794 * Once current->seccomp.mode is non-zero, it may not be changed.
796 * Returns 0 on success or -EINVAL on failure.
798 static long seccomp_set_mode_strict(void)
800 const unsigned long seccomp_mode
= SECCOMP_MODE_STRICT
;
803 spin_lock_irq(¤t
->sighand
->siglock
);
805 if (!seccomp_may_assign_mode(seccomp_mode
))
811 seccomp_assign_mode(current
, seccomp_mode
);
815 spin_unlock_irq(¤t
->sighand
->siglock
);
820 #ifdef CONFIG_SECCOMP_FILTER
822 * seccomp_set_mode_filter: internal function for setting seccomp filter
823 * @flags: flags to change filter behavior
824 * @filter: struct sock_fprog containing filter
826 * This function may be called repeatedly to install additional filters.
827 * Every filter successfully installed will be evaluated (in reverse order)
828 * for each system call the task makes.
830 * Once current->seccomp.mode is non-zero, it may not be changed.
832 * Returns 0 on success or -EINVAL on failure.
834 static long seccomp_set_mode_filter(unsigned int flags
,
835 const char __user
*filter
)
837 const unsigned long seccomp_mode
= SECCOMP_MODE_FILTER
;
838 struct seccomp_filter
*prepared
= NULL
;
841 /* Validate flags. */
842 if (flags
& ~SECCOMP_FILTER_FLAG_MASK
)
845 /* Prepare the new filter before holding any locks. */
846 prepared
= seccomp_prepare_user_filter(filter
);
847 if (IS_ERR(prepared
))
848 return PTR_ERR(prepared
);
851 * Make sure we cannot change seccomp or nnp state via TSYNC
852 * while another thread is in the middle of calling exec.
854 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
&&
855 mutex_lock_killable(¤t
->signal
->cred_guard_mutex
))
858 spin_lock_irq(¤t
->sighand
->siglock
);
860 if (!seccomp_may_assign_mode(seccomp_mode
))
863 ret
= seccomp_attach_filter(flags
, prepared
);
866 /* Do not free the successfully attached filter. */
869 seccomp_assign_mode(current
, seccomp_mode
);
871 spin_unlock_irq(¤t
->sighand
->siglock
);
872 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
873 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
875 seccomp_filter_free(prepared
);
879 static inline long seccomp_set_mode_filter(unsigned int flags
,
880 const char __user
*filter
)
886 static long seccomp_get_action_avail(const char __user
*uaction
)
890 if (copy_from_user(&action
, uaction
, sizeof(action
)))
894 case SECCOMP_RET_KILL_PROCESS
:
895 case SECCOMP_RET_KILL_THREAD
:
896 case SECCOMP_RET_TRAP
:
897 case SECCOMP_RET_ERRNO
:
898 case SECCOMP_RET_TRACE
:
899 case SECCOMP_RET_LOG
:
900 case SECCOMP_RET_ALLOW
:
909 /* Common entry point for both prctl and syscall. */
910 static long do_seccomp(unsigned int op
, unsigned int flags
,
911 const char __user
*uargs
)
914 case SECCOMP_SET_MODE_STRICT
:
915 if (flags
!= 0 || uargs
!= NULL
)
917 return seccomp_set_mode_strict();
918 case SECCOMP_SET_MODE_FILTER
:
919 return seccomp_set_mode_filter(flags
, uargs
);
920 case SECCOMP_GET_ACTION_AVAIL
:
924 return seccomp_get_action_avail(uargs
);
930 SYSCALL_DEFINE3(seccomp
, unsigned int, op
, unsigned int, flags
,
931 const char __user
*, uargs
)
933 return do_seccomp(op
, flags
, uargs
);
937 * prctl_set_seccomp: configures current->seccomp.mode
938 * @seccomp_mode: requested mode to use
939 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
941 * Returns 0 on success or -EINVAL on failure.
943 long prctl_set_seccomp(unsigned long seccomp_mode
, char __user
*filter
)
948 switch (seccomp_mode
) {
949 case SECCOMP_MODE_STRICT
:
950 op
= SECCOMP_SET_MODE_STRICT
;
952 * Setting strict mode through prctl always ignored filter,
953 * so make sure it is always NULL here to pass the internal
954 * check in do_seccomp().
958 case SECCOMP_MODE_FILTER
:
959 op
= SECCOMP_SET_MODE_FILTER
;
966 /* prctl interface doesn't have flags, so they are always zero. */
967 return do_seccomp(op
, 0, uargs
);
970 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
971 long seccomp_get_filter(struct task_struct
*task
, unsigned long filter_off
,
974 struct seccomp_filter
*filter
;
975 struct sock_fprog_kern
*fprog
;
977 unsigned long count
= 0;
979 if (!capable(CAP_SYS_ADMIN
) ||
980 current
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
) {
984 spin_lock_irq(&task
->sighand
->siglock
);
985 if (task
->seccomp
.mode
!= SECCOMP_MODE_FILTER
) {
990 filter
= task
->seccomp
.filter
;
992 filter
= filter
->prev
;
996 if (filter_off
>= count
) {
1000 count
-= filter_off
;
1002 filter
= task
->seccomp
.filter
;
1003 while (filter
&& count
> 1) {
1004 filter
= filter
->prev
;
1008 if (WARN_ON(count
!= 1 || !filter
)) {
1009 /* The filter tree shouldn't shrink while we're using it. */
1014 fprog
= filter
->prog
->orig_prog
;
1016 /* This must be a new non-cBPF filter, since we save
1017 * every cBPF filter's orig_prog above when
1018 * CONFIG_CHECKPOINT_RESTORE is enabled.
1028 get_seccomp_filter(task
);
1029 spin_unlock_irq(&task
->sighand
->siglock
);
1031 if (copy_to_user(data
, fprog
->filter
, bpf_classic_proglen(fprog
)))
1034 put_seccomp_filter(task
);
1038 spin_unlock_irq(&task
->sighand
->siglock
);
1043 #ifdef CONFIG_SYSCTL
1045 /* Human readable action names for friendly sysctl interaction */
1046 #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
1047 #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
1048 #define SECCOMP_RET_TRAP_NAME "trap"
1049 #define SECCOMP_RET_ERRNO_NAME "errno"
1050 #define SECCOMP_RET_TRACE_NAME "trace"
1051 #define SECCOMP_RET_LOG_NAME "log"
1052 #define SECCOMP_RET_ALLOW_NAME "allow"
1054 static const char seccomp_actions_avail
[] =
1055 SECCOMP_RET_KILL_PROCESS_NAME
" "
1056 SECCOMP_RET_KILL_THREAD_NAME
" "
1057 SECCOMP_RET_TRAP_NAME
" "
1058 SECCOMP_RET_ERRNO_NAME
" "
1059 SECCOMP_RET_TRACE_NAME
" "
1060 SECCOMP_RET_LOG_NAME
" "
1061 SECCOMP_RET_ALLOW_NAME
;
1063 struct seccomp_log_name
{
1068 static const struct seccomp_log_name seccomp_log_names
[] = {
1069 { SECCOMP_LOG_KILL_PROCESS
, SECCOMP_RET_KILL_PROCESS_NAME
},
1070 { SECCOMP_LOG_KILL_THREAD
, SECCOMP_RET_KILL_THREAD_NAME
},
1071 { SECCOMP_LOG_TRAP
, SECCOMP_RET_TRAP_NAME
},
1072 { SECCOMP_LOG_ERRNO
, SECCOMP_RET_ERRNO_NAME
},
1073 { SECCOMP_LOG_TRACE
, SECCOMP_RET_TRACE_NAME
},
1074 { SECCOMP_LOG_LOG
, SECCOMP_RET_LOG_NAME
},
1075 { SECCOMP_LOG_ALLOW
, SECCOMP_RET_ALLOW_NAME
},
1079 static bool seccomp_names_from_actions_logged(char *names
, size_t size
,
1082 const struct seccomp_log_name
*cur
;
1083 bool append_space
= false;
1085 for (cur
= seccomp_log_names
; cur
->name
&& size
; cur
++) {
1088 if (!(actions_logged
& cur
->log
))
1092 ret
= strscpy(names
, " ", size
);
1099 append_space
= true;
1101 ret
= strscpy(names
, cur
->name
, size
);
1112 static bool seccomp_action_logged_from_name(u32
*action_logged
,
1115 const struct seccomp_log_name
*cur
;
1117 for (cur
= seccomp_log_names
; cur
->name
; cur
++) {
1118 if (!strcmp(cur
->name
, name
)) {
1119 *action_logged
= cur
->log
;
1127 static bool seccomp_actions_logged_from_names(u32
*actions_logged
, char *names
)
1131 *actions_logged
= 0;
1132 while ((name
= strsep(&names
, " ")) && *name
) {
1133 u32 action_logged
= 0;
1135 if (!seccomp_action_logged_from_name(&action_logged
, name
))
1138 *actions_logged
|= action_logged
;
1144 static int seccomp_actions_logged_handler(struct ctl_table
*ro_table
, int write
,
1145 void __user
*buffer
, size_t *lenp
,
1148 char names
[sizeof(seccomp_actions_avail
)];
1149 struct ctl_table table
;
1152 if (write
&& !capable(CAP_SYS_ADMIN
))
1155 memset(names
, 0, sizeof(names
));
1158 if (!seccomp_names_from_actions_logged(names
, sizeof(names
),
1159 seccomp_actions_logged
))
1165 table
.maxlen
= sizeof(names
);
1166 ret
= proc_dostring(&table
, write
, buffer
, lenp
, ppos
);
1173 if (!seccomp_actions_logged_from_names(&actions_logged
,
1177 if (actions_logged
& SECCOMP_LOG_ALLOW
)
1180 seccomp_actions_logged
= actions_logged
;
1186 static struct ctl_path seccomp_sysctl_path
[] = {
1187 { .procname
= "kernel", },
1188 { .procname
= "seccomp", },
1192 static struct ctl_table seccomp_sysctl_table
[] = {
1194 .procname
= "actions_avail",
1195 .data
= (void *) &seccomp_actions_avail
,
1196 .maxlen
= sizeof(seccomp_actions_avail
),
1198 .proc_handler
= proc_dostring
,
1201 .procname
= "actions_logged",
1203 .proc_handler
= seccomp_actions_logged_handler
,
1208 static int __init
seccomp_sysctl_init(void)
1210 struct ctl_table_header
*hdr
;
1212 hdr
= register_sysctl_paths(seccomp_sysctl_path
, seccomp_sysctl_table
);
1214 pr_warn("seccomp: sysctl registration failed\n");
1216 kmemleak_not_leak(hdr
);
1221 device_initcall(seccomp_sysctl_init
)
1223 #endif /* CONFIG_SYSCTL */